In the printing of packaging with multi-color images, individual printing plates are prepared for each individual color to be printed and the individual color images are printed onto the recipient surface, for example, a paperboard or corrugated sheet from which a carton is to be produced, to produce the overall desired multi-color image on the recipient surface.
In order for the correct desired image to be printed on the recipient surface, it is necessary to properly mount the individual color printing plates on a carrier sheet. With flexographic printing plates, often such printing plates are made up of relatively small flexographic printing plate elements, particularly for cartons with large imprinted portions.
Attempting to ensure that the printing plate elements are correctly positioned on the carrier sheet is a time-consuming operation requiring considerable skill. For each individual color to be printed, it is necessary first for the mounter to draw the outline of the carton which is to be printed on a mounting carrier sheet as well as the location of the various score lines and then determining the intended location of the printing image for the specific color for which the mounter is preparing the printing plate by measurement. The mounter then affixes the individual flexographic printing plate elements to the locations on the printing blanket determined in this way. The procedure is repeated for each individual color to be printed to provide individual one-color printing plates, which then are mounted on the printing machine for printing the recipient surface.
As well as being time consuming, the mounting operation requires skill to locate the flexographic printing plate elements in the correct location on the carrier sheet once the outline has been drawn and the measurements have been made on the carrier sheet. The exact positioning of the elements is determined visually by the mounter and may be inaccurate.